Prefabricated wooden trusses are being utilized in the construction industry. Such trusses are typically assembled at a manufacturing facility and then transported to the job site for incorporation into the building. The use of these prefabricated structures can result in substantial cost saving by decreasing the time and labor required to complete a project. In addition, these trusses are generally lighter in weight and more efficiently engineered than on-the-site assembled trusses.
Prefabricated wooden truss rafters for use as floor or roof supports are examples of components which are pre-assembled and used widely in the construction industry. Such trusses are assembled from pre-cut wooden chord and web members positioned in an abutting relationship and connected together by metal connector plates.
Although trusses of this type can be fabricated by hand on a production line basis, several truss assembly machines have been developed for performing this task in a semiautomated manner. One such machine is disclosed in prior U.S. Pat. No. 4,295,269 to Wright. In general, this patent discloses a device in which pre-cut wooden members are positioned manually over a support or work table. The members are clamped in place after which a toothed metal fastener is laid over the abutting joints. The fastener plates are pressed into the wooden members to secure the joints while the members are held by clamping assembly.
Various arrangements of tables and clamping assemblies have been employed in the prior art such as those shown in the above mentioned U.S. Pat. No. 4,295,269, and the patents cited therein. Typically, the truss components are laid flat on a table and abutted against a fixed brace. A clamping assembly is positioned on the opposite side of the truss and is movable between an open and closed position. In the open position, sufficient space is provided between the fixed brace and the clamping assembly to allow placement of the truss components therebetween. In a closed position, the clamp closes on the truss components and clamps or presses them against the fixed brace. In the prior art, this clamping means comprised an elongated bar of a sufficient length to contact one side of the truss and a mechanical device such as a screw, lever or toggle means is provided to apply closing force to the elongated member at spaced points. In other prior art devices, pneumatic or hydraulic cylinders contact the elongated member at spaced points and apply force thereto. The prior art clamping apparatus which contact the elongate member at space points can in some cases tend to deform the elongate member and truss assembly itself. This limits the capability of the prior art truss manufacturing devices.